2d4f3e2ac9
The layer is now redundant, since everything left in "pkgs" is in the "racket-pkgs" category.
60 lines
1.9 KiB
Racket
60 lines
1.9 KiB
Racket
#lang scribble/doc
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@(require "mz.rkt")
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@title[#:tag "load-lang"]{The @racketmodname[racket/load] Language}
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@defmodulelang[racket/load]
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The @racketmodname[racket/load] language supports evaluation where
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each top-level form in the module body is separately passed to
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@racket[eval] in the same way as for @racket[load].
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The namespace for evaluation shares the @tech{module registry} with
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the @racketmodname[racket/load] module instance, but it has a separate
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top-level environment, and it is initialized with the bindings of
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@racketmodname[racket]. A single namespace is created for each
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instance of the @racketmodname[racket/load] module (i.e., multiple
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modules using the @racketmodname[racket/load] language share a
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namespace). The @racket[racket/load] library exports only
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@racketidfont{#%module-begin} and @racketidfont{#%top-interaction}
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forms that effectively swap in the evaluation namespace and call
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@racket[eval].
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For example, the body of a module using @racket[racket/load] can
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include @racket[module] forms, so that running the following module
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prints @racketresultfont{5}:
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@racketmod[
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racket/load
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(module m racket/base
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(provide x)
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(define x 5))
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(module n racket/base
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(require 'm)
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(display x))
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(require 'n)
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]
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Definitions in a module using @racket[racket/load] are evaluated in
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the current namespace, which means that @racket[load] and
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@racket[eval] can see the definitions. For example, running the
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following module prints @racketresultfont{6}:
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@racketmod[
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racket/load
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(define x 6)
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(display (eval 'x))
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]
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Since all forms within a @racketmodname[racket/load] module are
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evaluated in the top level, bindings cannot be exported from the
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module using @racket[provide]. Similarly, since evaluation of the
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module-body forms is inherently dynamic, compilation of the module
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provides essentially no benefit. For these reasons, use
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@racketmodname[racket/load] for interactive exploration of top-level
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forms only, and not for constructing larger programs.
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